Typical computer systems, especially computer systems having graphical user interfaces (“GUIs”), are optimized for accepting user input from one or more discrete input devices, such as a keyboard for entering text and a pointing device, such as a mouse with one or more buttons, for operating and interacting with the user interface. An example of such a GUI is the user interface for the Windows® computer operating system (available from Microsoft Corporation of Redmond, Wash.). The ubiquitous keyboard and mouse interface provides for fast creation and modification of documents, spreadsheets, database fields, drawings, photos, web pages, emails, and the like.
Recently, however, pen-based computing systems, such as tablet personal computers (“tablet PCs”), personal digital assistants (“PDAs”), and the like, have been increasing in popularity. With pen-based computing systems, user input advantageously may be introduced as “electronic ink” and/or by mimicking writing using an electronic “pen” or stylus (e.g., mimicking writing with a pen or pencil on a piece of paper). Indeed, in at least some pen-based computing systems, all user input is capable of being entered and manipulated using an electronic pen input device, and the user interface is fully controllable using only the electronic pen.
Electronic or digital pens also are commercially available that enable users to write in conventional ink on a conventional piece of paper while, at the same time, electronically capturing and storing the handwritten input as electronic data (e.g., as electronic ink data, as image data, as recognized text data based on the ink input, etc.). Such electronic or digital pen products are commercially available from a variety of commercial sources.
The ability to electronically capture handwritten strokes can be beneficial in many ways. For example, the use of electronic or digital pens or styli provides familiar and well known input systems and methods that enable many users to quickly, easily, and conveniently input or generate electronic data that, in at least some instances, can be electronically captured, converted to machine-readable text, and/or stored.
In at least some instances, however, a person's handwriting can convey information in ways other than through the bare meaning of the strokes or words on the page. For example, the physical appearance of strokes on a page may convey information to the viewer. As more specific examples, the thickness or heaviness of a line, stroke, or word, optionally together with the underlying content of the writing in context, may provide information to the reader as to the writer's state of mind when making the writing (e.g., heavy or thick lines may indicate an agitated, excited, or angry state of mind, etc.), may indicate an intent to accent or stress certain information, etc.
In order to capture line thickness or other similar information when writing with electronic pens and/or in electronic ink, and to thereby enable better display or reproduction of the handwriting (e.g., as electronic ink or in printed form), some electronic pens or styli have been designed to include on-board writing force or pressure sensors in the form of resistor systems for measuring force. Conventional electronic pen or styli devices of this type typically have at least some portion of the force sensing system oriented normal to the direction of the incident writing force (i.e., perpendicular to the axis of the pen). This orientation, however, tends to increase the electronic pen's or stylus's cross-sectional area or width in the grip zone due to the footprint of the force sensing system, which tends to make the pen or stylus uncomfortably thick or difficult to use. Moreover, this conventional sensor structure must be properly aligned in the overall pen structure. Accordingly, it would be advantageous to provide an electronic pen or stylus that has dimensions more typical of a conventional ballpoint pen that is easy to build and mount, and that provides accurate and simple measurements of writing force or pressure.